1. Field of the Invention
The present invention relates to an apparatus for deciding whether or not a seam of a molded golf ball is placed in a predetermined position in order to remove a spew present on the same seam.
2. Description of the Related Art
Usually, a golf ball is molded by upper and lower molds comprising semispherical cavities, respectively. For a molding method, injection molding, compression molding and the like are employed. In any of the molding methods, it is impossible to prevent a material (rubber, synthetic resin or the like) from slightly leaking out of a parting line of the upper and lower molds. Accordingly, a ring-shaped spew formed of the material is generated in a portion (hereinafter referred to as a xe2x80x9cseamxe2x80x9d) corresponding to the parting line on the surface of the molded golf ball. The golf ball obtained immediately after the molding has a golf ball body and a spew present on the seam over the surface of the golf ball body. The spew should be removed.
The spew is removed by rotating the golf ball chucked by a holding member and causing the spew to abut on a cutting tool such as a grindstone, a sandpaper or a cutter blade. During the rotation of the golf ball, the positional relationship between the spew and the cutting tool should be maintained to be constant. For this reason, the golf ball is chucked such that a rotation axis is orthogonal to a plane including a seam. The golf ball is usually chucked such that the seam is maintained to be horizontal or vertical.
The golf ball has been chucked manually for a long time. Therefore, a work efficiency has been poor and the cost of manufacture of the golf ball has been increased.
There has also been proposed a spew removing apparatus for mechanically positioning a golf ball without depending on a handwork such that a seam is horizontal (positioning step) and then cutting a spew (cutting step). Such a spew removing apparatus has been disclosed in Japanese Laid-Open Patent Publication No. Sho 59-81059 (1984/81059), Japanese Laid-Open Patent Publication No. Sho 60-232861 (1985/232861), Japanese Laid-Open Patent Publication No. Sho 63-174801 (1988/174801), Japanese Laid-Open Patent Publication No. Sho 63-11266 (1988/11266) and Japanese Laid-Open Patent Publication No. Hei 8-229810 (1996/229810). In these spew removing apparatuses, however, the precision of the positioning step is insufficient. In some golf balls obtained through the positioning step, accordingly, a seam is not horizontal. If the seam is not horizontal, the spew cannot be removed completely at a subsequent cutting step or a portion other than the seam on the surface of the golf ball abuts on a cutting tool and is thereby cut. Consequently, a defective product is manufactured.
In order to prevent the defective product from being manufactured, the step of deciding whether or not the seam is placed in a predetermined position (for example, horizontally) is provided between the positioning step and the cutting step. Only a golf ball decided to have a seam which is horizontal is transferred to the cutting step and a golf ball decided to have a seam which is not horizontal is returned to the positioning step again. For such deciding means, there has been known means for rotating a golf ball after the positioning step and deciding the presence of a seam in a contact portion through a vibration sensor to come in contact with the surface of the golf ball. Moreover, there has also been used means for deciding the presence of a seam in a predetermined position through a fluctuation in a voltage signal of infrared rays or the like. However, any means often makes an erroneous decision. Therefore, it has been desirable that the precision in a decision should be enhanced in respect of a reduction in the rate of generation of defective products.
In consideration of such circumstances, it is an object of the present invention to provide a seam position deciding apparatus capable of deciding, with high precision, whether or not a seam is placed in a predetermined position and a method of manufacturing a golf ball using the seam position deciding apparatus.
In order to achieve the above-mentioned object, the present invention provides an apparatus for deciding whether or not a seam is placed in a predetermined position, comprising a camera for photographing a golf ball having a spew present on the seam thereof, and operating means for deciding presence of a spew in a predetermined region of an image photographed by the camera.
In the seam position deciding apparatus, whether the seam is placed in the predetermined position is decided based on the image photographed by the camera. In the deciding method, precision in a decision is more excellent than that in a conventional deciding method. The decision is made based on the numbers of black pixels and white pixels in the predetermined region of the image.
Preferably, the photographing is carried out by the camera while the golf ball is rotated and it is decided whether or not the seam is placed in the predetermined position. Consequently, the rate of an erroneous decision can be reduced still more.
The seam position deciding apparatus is excellent in the precision in a decision. In a golf ball manufacturing method using the seam position deciding apparatus, therefore, the rate of generation of defective products can be reduced.